1. Field of the Invention
This invention relates to an apparatus for applying a plurality of surgical fasteners to body tissue and more particularly to an apparatus for simultaneously applying a plurality of two part bioabsorbable surgical fasteners.
2. Description of the Prior Art
Surgical fastener applicator apparatus in which surgical fasteners are simultaneously applied to body tissue are known. Typically, these devices include a fastener holder positioned on one side of the tissue to be fastened and an anvil parallel to the fastener holder positioned on the other side of the tissue. Typically, means is provided for linearly translating the fastener holder and the anvil toward one another to clamp the tissue between them. Means is also provided for driving the fasteners from the fastener holder so that the ends of the fasteners pass through the tissue and form finished fasteners as they make contact with the anvil assembly, thereby producing an array of finished fasteners in the tissue.
Also in use are instruments for applying two part fasteners having a fastener portion and a retainer portion. The fastener portion generally has barbed prongs for penetrating body tissue and engaging corresponding openings in the retainer portion. Once engaged, the fastener and retainer are locked together. Such two-part fasteners are usually constructed from bioabsorbable material.
In common use are apparatus in which the fastener holder and anvil are removably mounted in or on an actuator for supporting and actuating the cartridge. The apparatus can be disposed of after a single use or it can be reused for another surgical fastening procedure after cleaning, sterilizing and reloading with a fresh cartridge. Also in use are fully disposable surgical instruments in which the cartridge and actuator are preassembled ready for use and disposed of after only a single use.
U.S. Pat. No. 4,665,916 (Green) describes a surgical fastener apparatus for applying rows of fasteners laterally through hollow body organs such as the thorax, trachea, stomach, uterus or intestines. The cartridge includes an alignment pin which achieves and maintains proper relative positioning of the fastener holder and anvil components thereof. When the fully assembled instrument is actuated, it is positioned in such a way that the body tissue to be fastened is clamped in place between the staple-ejecting surface of the fastener holder and the anvil assembly. The clamping pressure exerted against both sides of the tissue is sufficient to provide effective hemostasis along two linear sites which, upon "firing" of the instrument, receive substantially parallel rows of fasteners on either side of an incision formed by a tissue cutting knife which is also incorporated in the holder. The deployment of the knife is mechanically synchronized to immediately follow the insertion of the fasteners.
U.S. Pat. No. 4,819,853 (Green) discloses a surgical fastener applicator which includes tissue gripping elements provided along the sides of a knife slot to prevent body tissue from pulling away from the fasteners after the latter are positioned in place and the incision is made. Thereafter, clamping pressure is released.
U.S. Pat. No. 4,881,545 (Isaacs et al.) discloses a surgical fastener cartridge possessing an improved body cutting knife assembly. The knife element of the assembly is held in permanent locking engagement with a knife holder.
U.S. Pat. No. 4,767,044 (Green) discloses a fastener applying apparatus including means for preventing all of the fasteners from reaching peak formation force at the same time in order to reduce the maximum force required to operate the apparatus.
U.S. Pat. No. 4,728,020 (Green et al.) discloses an articulated surgical fastener applying apparatus having a linear drive mechanism which is offset from the centerline of movement of the surgical fasteners. The drive force is proximally directed, i.e. it is a pulling force transmitted by a tensioned cable mechanism rather than by a drive rod.
While the prior art instruments, such as those mentioned above, have been serving the needs of the medical community by providing surgeons with quick and simple means to make and/or seal incisions in body tissue, improvements are nevertheless desirable. For example, surgeons prefer to have a greater visibility of the area of tissue upon which they are operating. It should be noted that in the prior art instruments, the drive rod for driving the fastener pushers operates axially and is centered at the rear of the fastener holding cartridge. The longitudinal frame of the instrument, therefore, often interferes with the surgeon's line of sight and obstructs visibility of the operation site.
An off-centered axially moving drive rod would therefore be desirable since it would enable the surgeon to have greater visibility of the operating site. Up to now however, the use of an off-centered drive rod has not been recognized as a solution to the problem. Unlike the cable drive means, the drive rod operates by applying a distally directed, or "pushing" drive force. The central location of the drive rod of the prior art instruments prevents the fastener pushers and the knife, if there is one, from pivoting and jamming within the fastener holding cartridge due to the critical location of the force. Such jamming would occur if the fastener pushers were driven by an off-center force in previously known instruments. Moreover, cable drive means restrict the ability of prior art instruments to be "reset" after initial firing.
The present invention provides such an apparatus in which improved visibility of the operation site is facilitated while avoiding direct off-centered driving force application to the fastener pushing members.